Advertising
Having the president's image in an advertisement--especially that of Washington, Theodore Roosevelt, or Lincoln--helped legitimize a product and separate it from the competition. The presidential name or representation instantly made an item recognizable and in demand. In the 20th century, an unwritten rule discourages the use of an image of the current president to advertise goods.
In the early 20th century, the image of Theodore Roosevelt was popular among advertisers. His vigor, enthusiastic personality, and credibility as both president and war hero lent legitimacy to any product. Here Roosevelt's reputation as an international adventurer is used to sell ABA Travelers Cheques.
Advertising cards were created by wholesalers as attractive items that retailers could give customers to remind them what brands to purchase. In use primarily from the years just after the Civil War through the early 20th century, these cards quickly became collectibles.
Companies used presidential images like this of John Adams--here gracing a card about Sweet Home Soap--to encourage the acquisition of their product. This prompted sales, and the advertising cards allowed people to collect a bit of the presidency for themselves.